X-Y stages are well known; they are typically used in machine tools and other applications where two dimensional precise movement is needed to position an object. An application of X-Y stages is in lithography equipment e.g. for semiconductor wafer processing. In this case, a stage is typically used in a lithography tool to position in two dimensions the reticle (mask). A separate stage is sometimes provided to position the semiconductor wafer. Such lithographically tools typically include a source of radiant energy for illumination such as a mercury or other lamp or laser or electron beam source, and a lens to focus the radiation which passes through the reticle onto the workpiece. This is an optical lens in the case of photolithography or an electron lens, which is an assembly of magnetic coils, in the case of an electron beam system.
In the case of electron beam systems, special problems are present since stray magnetic fields or electric currents may adversely affect the electron beam. Also mechanical and thermal disturbances are problematic since they reduce the resolution, positioning accuracy and positioning speed of the lithography process.
Hence there is a need for improved stages, particularly for use in electron beam lithography.